Pressure Effects Caused by CO2 Injection in the Snøhvit Field

A rock physics diagnostics study is performed for the Tubåen formation in the Snøhvit field with the aim of characterizing the transport properties for the different sand intervals. This is combined with co2 injection laboratory experiments for selected plugs from the sand intervals to understand the impact the CO2 injection have on the microstructure of the rock framework and its physical properties. The rock physics diagnostic indicates that parts of the Tubåen formation are dominated by stiff load bearing contact cement, other parts by pore-filling grains that can be related to poor sorting, and that don’t contribute to the stiffness of the rock. Some of these fine particles may become dislodged due to CO2 injection, which permanently changes the load bearing framework of the formation. The laboratory experiments and SEM images indicate that the CO2 injection cause a re-arrangement of the rock framework and of the movable fines that change the rock framework. The importance of fines migration is likely to depend on the initial microstructure of the rock. The results of the ongoing laboratory experiments will help to better understand the effect on the different sand intervals of the Tubåen formation.